This paper describes a social robotic game player that is able to successfully play a team card game called Sueca. The question we will address in this paper is: how can we build a social robot player that is able to balance its ability to play the card game with natural and social behaviours towards its partner and its opponents. The first challenge we faced concerned the development of a competent artificial player for a hidden information game, whose time constraint is the average human decision time. To accomplish this requirement, the Perfect Information Monte-Carlo (PIMC) algorithm was used. Further, we have performed an analysis of this algorithm's possible parametrizations for games trees that cannot be fully explored in a reasonable amount of time with a MinMax search. Additionally , given the nature of the Sueca game, such robotic player must master the social interactions both as a partner and as an opponent. To do that, an emotional agent framework (FAtiMA) was used to build the emotional and social behaviours of the robot. At each moment, the robot not only plays competitively but also appraises the situation and responds emotionally in a natural manner. To test the approach, we conducted a user study and compared the levels of trust participants attributed to the robots and to human partners. Results have shown that the robot team exhibited a winning rate of 60%. Concerning the social aspects, the results also showed that human players increased their trust in the robot as their game partners (similar to the way to the trust levels change towards human partners). As interactive entertainment expands, computer games are progressively moving from the virtual world back to the physical world. Augmented reality games, haptic interfaces in gaming, touch tables, etc, are some of the types of in-teractivity placing human players in physically situated entertainment experiences. In parallel with this move into the physical world, artificial partners and opponents can also be created to exist in such physical world. To do that, the area of entertainment robots offers challenging opportunities as it explores the role of a robot as a game player. In general, social robots can contribute with new and broad ways of creating socially engaging interactions with humans in entertainment contexts. The challenges of these human-robot interactions may vary from game to game. Some games, when played in the physical world not only hold complex social Copyright c 2017, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. behaviours, but they also hinder performance aspects related with the competitive nature of the game itself. Furthermore, in many types of games, current advances in Artificial Intelligence (AI) over the past few years has shown that strong and powerful algorithms combined with significant amounts of data, are able to defeat human world champions of these games (see for example, the game of Go). These results raise our expectations and people are starting to consider such artificial agents as fierce competitors. Yet, when we consider multi-player games, where the social environment becomes more relevant, and when the games are played in the physical world, how will people perceive a social robotic player compared to human standards? Will people be willing to trust a social robot to be his partner in a team game? To address these questions we created a social autonomous robotic partner for the Sueca card game, with a twofold goal of both playing competitively and interacting socially with the other players. The development of such robotic game player introduces some challenging aspects, in particular finding the best balance between social responses and computations related with the game, in order for the socially intelligent agent to produce natural and human-like behaviours. Another important challenge of creating an intelligent agent in this social context is the time constraint on the computation of a hidden information card game. State-of-the-art approaches, for instance PIMC, promise good results on the Sueca domain according to the game properties. However, the full computation of multiple perfect information games is not time-efficient and will hinder natural interaction in a game with human players. Therefore, this paper also explores how the algorithm's parametrizations affect the game results in order to choose the best performance-time configuration. Finally, by using an expressive robot that is able to express emotions, provide spoken feedback, and respond socially , the game experience can be created balancing these social and game competencies. In this case, we built the social competencies by using an emotional agent framework (FatiMA) which allows for emotional appraisal to occur and fire social and emotional behaviours. At each moment, the robot not only plays competitively, but also appraises the situation and responds emotionally to the game situations. 23 To evaluate such robotic game player, we have considered two central aspects for assessing when playing in the card game: (1) competitiveness between team opponents and (2) cooperation between team partners. Performance can be measured by the number of games won, and simulations made with the developed algorithm to test it against other artificial players. But, most importantly, to assess how humans perceive the robot as a game player we conducted a user study with 60 participants and measured the human players' trust levels in their partners (before and after playing). Concerning the competence of the robot, the results show that the robot is able to play competitively with human players, achieving a winning rate of 60%. We also compared the trust level on the robotic partner with the trust level on human partners. The results show that human players significantly increased their trust in the robot as their game partners (in a similar way to the trust levels they perceive to have towards human partners).